1. Field of the Invention
The present invention relates to a hook device which is applicable to a hoist, crane or the like. More particularly it relates to a hook device which safety is ensured during operation.
2. Description of the Prior Art
When a hoist or a crane is put in use under overload, a breakage thereof takes place from time to time, resulting in a terrible circumstance in which the operator or other person may be injured or killed.
In the meantime, even in less terrible circumstances without such breakage there will be seen certain wear in every section of the device, as well as fatigue of wire rope and others, all of which shortens substantially durability of the device. In view of these facts, it will be very useful and practicable, if the approximate value of the suspension load could be recognized by the operator and others in the vicinity in a simple manner, for instance, by way of visual inspection, etc.. Further it will be very preferable, if any signal of alarm could be issued to them, while overload is applied, so that a dangerous situation is prevented beforehand. Moreover it will be very desirable, if the number of times when load, particularly overload, is applied could be counted so as to indicate the time when maintenance, inspection and replacement are to be performed. It has been expected for a long time that the above requirements are sufficiently and satisfactorily met.